Numerous situations exist where it is important to limit the load or force applied to or borne by a lower natural or prosthetic limb or joint of the body during standing, walking, stepping, running or jumping activities or during rehabilitation therapy. Situations also exist where it is important that the lower limb or joint be exposed to a certain load or force, particularly during rehabilitation therapy. In both situations it is important to monitor such load or force and to provide a signal to the user when such force is exceeded or met. Examples include post-surgery or injury rehabilitation of hips, knees, ankles or any other portion of the body which is affected by force applied to or borne by at least one of the user's legs, or any other situation in which monitoring of the weight on a lower limb during standing, walking, jumping or other activities is desired.
Prior art systems for monitoring the load or force applied to joints in a patient's leg are found in U.S. Patent Application Pub. No. 2006/0282018 and in the following U.S. Pat. Nos. 3,702,999 (Gradisar); 3,791,375 (Pfeiffer); 3,974,491 (Sipe); 4,745,930 (Confer); 5,107,854 (Knotts et al); 5,253,654 (Thomas et al); 5,511,561 (Wanderman et al); 5,619,186 (Schmidt et al); 6,174,294 (Crabb et al); and 6,273,863 (Avni et al).
Prior art monitors are typically complex mechanically and/or electrically with the result that they are expensive and add significantly to a patient's cost of recuperation.